by Staff WritersReston, VA (SPX) Dec 02, 2010
Many coastal wetlands worldwide - including several on the U.S. Atlantic coast - may be more sensitive than previously thought to climate change and sea-level rise projections for the 21st century.

U.S. Geological Survey scientists made this conclusion from an international research modeling effort published in the journal Geophysical Research Letters, a publication of the American Geophysical Union. Scientists identified conditions under which coastal wetlands could survive rising sea level.

Using a rapid sea-level rise scenario, most coastal wetlands worldwide will disappear near the end of the 21st century. In contrast, under the slow sea-level rise projection, wetlands with low sediment availability and low tidal ranges are vulnerable and may drown. However, in the slow sea-level rise projection, wetlands with higher sediment availability would be more likely to survive.

Several coastal marshes along the east coast of the United States, for example, have limited sediment supplies and are likely to disappear this century. Vulnerable east coast marshes include the Plum Island Estuary (the largest estuary in New England) and coastal wetlands in North Carolina's Albemarle-Pamlico Sound (the second-largest estuary in the United States).

"Accurate information about the adaptability of coastal wetlands to accelerations in sea-level rise, such as that reported in this study, helps narrow the uncertainties associated with their disappearance," said USGS scientist Glenn Guntenspergen, an author of this report.

"This research is essential for allowing decision makers to best manage local tradeoffs between economic and conservation concerns."

"Previous assessments of coastal wetland responses to sea-level rise have been constrained because they did not consider the ability of wetlands to naturally modify their physical environment for adaptation," said USGS scientist Matt Kirwan, an author of this report.

"Failure to incorporate the interactions of inundation, vegetation and sedimentation in wetlands limits the usefulness of past assessments."

USGS scientists specifically identified the sediment levels and tidal ranges (difference between high and low tide) necessary for marshes to survive sea-level rise.

As water floods a wetland and flows through its vegetation, sediment is carried from upstream and deposited on the wetland's surface, allowing it to gain elevation. High tidal ranges allow for better sediment delivery, and the higher sediment concentrations in the water allow wetlands to build more elevation.

The rapid sea-level rise scenario used as the basis for this study is accredited to Stefan Rahmstorf at Potsdam University, one of the contributing authors of the Intergovernmental Panel on Climate Change Fourth Assessment Report. The slow sea-level rise projection is from the A1B scenario of the Intergovernmental Panel on Climate Change Fourth Assessment Report.

The study, "Limits on the Adaptability of Coastal Marshes to Rising Sea-Level," can be found online. Any journalists who are not registered with AGU and cannot view this article can contact USGS to have a copy emailed to them.

Rainforest Conservation Needs A New Direction To Address Climate ChangeUniversity Park PA (SPX) Dec 02, 2010Conservation and international aid groups may be on the wrong course to address the havoc wreaked by climate change on tropical rainforests, according to a commentary appearing in the journal Nature on 2 December 2010.
"Most of the world's terrestrial biodiversity is contained in tropical rainforests, and climate change is looming ever larger as one of the major threats to these ecosystems ... read more

The content herein, unless otherwise known to be public domain, are Copyright 1995-2010 - SpaceDaily. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement